Acyclic anionic six-electron-donor ancillary ligands

ABSTRACT

The present invention provides an improved acyclic anionic six-electron-donor ancillary ligand suitable for being bonded in a transition metal complex. The present invention also provides a transition metal complex that includes at least one acyclic anionic six-electron-donor ancillary ligand which is suitable for use as an olefin polymerization catalyst. The complex includes a Group 3 to 10 transition or lanthanide metal and one or more anionic or neutral ligands in an amount that satisfies the valency of the metal such that the complex has a net zero charge. The present invention also discloses a method for making transition metal complex and a method for using the complex for olefin polymerization.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to transition metal complexes withancillary ligands, and in particular, to acyclic anionic six-electrondonor ancillary ligands.

[0003] 2. Background Art

[0004] The chemical industry uses a wide variety of transition metalcomplexes as catalysts for organic reactions. Olefin polymerization isan important example of such a reaction. While conventionalZiegler-Natta catalysts continue to dominate the industry, highly activemetallocene or single-site catalysts which provide polymers withproperties such as narrow molecular weight distributions, low densities,and good co-monomer incorporation, are emerging.

[0005] Transition metal complexes used to polymerize olefins arenormally non-zero-valent metals (e.g., Ti⁴⁺, Zr⁴⁺, Sc³⁺) surrounded byanionic ligands (e.g., chloride, alkyl, cyclopentadienyl) that satisfythe valency of the metal. The nature of the various anionic ligands candramatically affect catalyst activity and polymer properties. Thus, byvarying the choice of anionic ligand, a catalyst structure can befine-tuned to produce polymers with desirable properties. Furthermore,the anionic ligand will affect the stability of the transition metalcomplexes.

[0006] Metallocene polymerization catalysts contain one or twocyclopentadienyl groups as anionic ligands. These serve to stabilize theactive catalytic species, modulate the electronic and steric environmentaround the active metal center, and maintain the single-site nature ofthe catalyst. Polymers with narrow molecular weight and compositiondistributions may be produced using these metallocene catalysts. Suchcomplexes frequently contain substituted cyclopentadienyl groups. Byutilizing substituted cyclopentadienyl moieties, the geometry andelectronic character of the active site may be altered, thus alteringthe activity and stability of the catalyst as well as the properties ofthe polyolefins produced therefrom.

[0007] Further anionic ligands are those which are heteroatomic ringligands isolobal to the cyclopentadienyl ring; that is, the orbitalinteraction of the metal with the ligand is similar in both cases.Examples of such ligands are boraaryl (see, e.g., U.S. Pat. No.5,554,775), pyrrolyl and indolyl anions (U.S. Pat. No. 5,539,124),azaborolinyl groups (U.S. Pat. No. 5,902,866), phospholyl anions, andtris(pyrazolyl)borate anions.

[0008] Transition metal complexes with highly delocalized cyclic anionicsix-electron-donor ancillary ligands are important precursors for avariety of highly efficient catalysts. The performance and cost of thesecatalysts are strongly dependent on the structure of the ligands. Itwould be desirable to provide transition metal complex catalysts inaddition to those presently available in order to provide furtheroptions with regard to catalytic activity and stability and polyolefinproduct properties.

SUMMARY OF THE INVENTION

[0009] In one embodiment of the present invention, a delocalized anionicacyclic ligand capable of providing six electrons when coordinated to atransition metal is provided. The structure of the ligand of the presentinvention is given by:

[0010] where A is CH₂, CHR³, CR³R⁴, NR³, O, S, or PR³; R¹ and R² areeach independently hydrogen, an aryl group, preferably a C₆₋₁₅ arylgroup, a C₆₋₁₅ arylphospho group (each aryl is C₆₋₅), a C₆₋₁₅ arylthiogroup, C₇₋₁₅ aralkyl group, C₁₋₁₀ alkoxy group, C₆₋₁₄ aryloxy group, aC₁₋₁₀ dialkylamino group (each alkyl is C₁₋₁₀), or a C₆₋₁₅ diarylaminogroup (each aryl is C₆₋₁₅); R³ and R⁴ are each independently hydrogen, aC₁₋₈ alkyl group, C₆₋₁₀ aryl group, or C₇₋₁₅ aralkyl group; and Y is B,Al, or Ga. It should be noted that in compounds containing “C₆₋₁₅diaryl” groups and similar designations, the C₆₋₁₅ refers to each arylgroup rather than the total carbon content of the ligand.

[0011] In another embodiment of the present invention, a transitionmetal complex incorporating the ligand of structure I is provided. Thestructure of the complex of the present invention is:

[0012] where M is a transition metal; L is a sigma bonded or pi bondedligand; n is an integer such that the valency of M is satisfied; A isCH₂, CHR³, CR³R⁴, NR³, O, S, and PR³; R¹ and R² are each independentlyhydrogen, C₆₋₁₀ aryl, diarylphospho, C₁₋₈ alkylthio, C₆₋₁₅ arylthio,C₇₋₁₅ aralkyl, C₁₋₁₀ alkoxy group, C₆₋₁₄ aryloxy group, C₁₋₁₀dialkylamino group, or C₆₋₁₅ diarylamino group; R³ and R⁴ are eachindependently hydrogen, C₁₋₈ alkyl, C₆₋₁₀ aryl, C₇₋₁₅ aralkyl, C₁₋₁₀alkoxy, C₆₋₁₄ aryloxy, C₁₋₁₀ dialkylamino, or C₆₋₁₅ diarylamino, and Yis B, Al, or Ga.

[0013] In still another embodiment of the present invention, a methodfor forming the metal complex having the ligand of the present inventionis provided. The method comprises reacting a ligand precursor having thefollowing structure:

[0014] where Z is a leaving group, with a metal compound with thestructure:

X—M—Ln  IV

[0015] where X is a halogen, to form metal complex II. L and n are asdefined above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Reference will now be made in detail to presently preferredcompositions or embodiments and methods of the invention, whichconstitute the best modes of practicing the invention presently known tothe inventor. It should be noted that the term “six-electron-donorancillary ligands” refers to ligands capable of bonding to a metal atomthrough six electrons.

[0017] In one embodiment of the present invention, a delocalized anionicacyclic ligand capable of providing six electrons while coordinated to atransition metal is provided. The structure of the ligand of the presentinvention is given by:

[0018] where A is CH₂, CHR³, CR³R⁴, NR³, O, S, or PR³; R¹ and R² areeach independently hydrogen, C₆₋₁₀ aryl, a C₆₋₁₅ diarylphospho group(each aryl is C₆₋₁₅), a C₁₋₁₈ alkylthio group, a C₆₋₁₅ arylthio group,C₇₋₁₅ aralkyl group, C₁₋₁₀ alkoxy group, C₆₋₁₄ aryloxy group, a C₁₋₁₀dialkylamino group (each alkyl is C ₁₋₁₀), or C₆₋₁₅ diarylamino group(each aryl is C₆₋₁₅); R³ and R⁴ are each independently hydrogen, a C₁₋₈alkyl group, C₆₋₁₀ aryl group, or C₇₋₁₅ aralkyl group; and Y is B, Al,or Ga. Furthermore, R¹ and R² may optionally be bonded to form a cyclicstructure.

[0019] In a preferred embodiment of the present invention, the anionicligand is given by the formula V:

[0020] where R¹ and R² are the same as above; R⁵ and R⁶ areindependently hydrogen, a C₁₋₈ alkyl group, C₆₋₁₀ aryl group, C₇₋₁₅aralkyl group, C₁₋₁₀ alkoxy group, C₆₋₁₄ aryloxy group, C₁₋₁₀dialkylamino group, or C₆₋₁₅ diarylamino group. In a refinement of thisembodiment a preferred ligand is given by formula VI:

[0021] where R⁵ and R⁶ are the same as above; R⁷ and R⁸ areindependently a C₁₋₁₈ alkyl group, C₆₋₁₀ aryl group, or C₇₋₁₅ aralkylgroup. Examples of this refinement include but are not limited tocompounds given by structures VII and VIII:

[0022] VIII

[0023] In another refinement of the ligand of structure V, a preferredligand is given by structure IX:

[0024] where R⁵ and R⁶ are the same as above and R⁹, R¹⁰, R¹¹, and R¹²are independently a C₁₋₈ alkyl group, C₆₋₁₀ aryl group, or C₇₋₁₅ aralkylgroup.

[0025] Another preferred ligand is provided by the group illustrated bystructure X:

[0026] where Y, R¹, R², and R³ are as provided above. In a variation ofthis preferred embodiment, the anionic ligand is described by structureXI:

[0027] where Y, R³, R⁷, and R⁸ are as provided above.

[0028] Another preferred ligand is provided by the group illustrated bystructure XII:

[0029] where Y, R¹, R², and R³ are as provided above.

[0030] Another preferred ligand is provided by the group illustrated bystructure XIII:

[0031] where Y, R¹, and R² are as provided above.

[0032] Another preferred ligand is provided by the group illustrated bystructure XIV:

[0033] where Y, R¹, and R² are as provided above.

[0034] In another embodiment of the present invention, a transitionmetal complex incorporating the ligand of structure I is provided. Thestructure of the complex of the present invention is:

[0035] where M is a transition metal; L is a sigma bonded or pi bondedligand; n is an integer such that the valency of M is satisfied; A isCH₂, CHR³, CR³R⁴, NR³, O, S, and PR³; R¹ and R² are each independentlyhydrogen, a C₆₋₁₅ diarylphospho group, a C₁₋₁₈ alkylthio group, a C₆₋₁₅arylthio group, C₇₋₁₅ aralkyl group, C₁₋₁₀ alkoxy group, C₆₋₁₄ aryloxygroup, C₁₋₁₀ dialkylamino group, or C₆₋₁₅ diarylamino group; and Y is B,Al, or Ga. The transition metal M is preferably a Group 3 to 10transition or lanthanide metal. Preferred Group 3 to 10 metals compriseSc, Ti, Cr, Mn, Fe, Co, Ni, and elements directly below these in thePeriodic Table. Preferred lanthanide metals include La, Ce, Pr, Eu, Yb,and the like. More preferably, the transition metal complex comprises aGroup 3 to ₆ transition or lanthanide metal, and most preferably, aGroup 4 transition metal. The sigma bonded or pi bonded ligands, L, arepreferably one or more anionic or neutral ligands. The one or moreanionic or neutral ligands are present in an amount determined by n suchthat the valency of M is satisfied. Examples include unsubstituted andsubstituted cyclopentadienyl, indenyl, fluorenyl, hydride, halide,alkyl, aryl, aralkyl, dialkylamino, siloxy, alkoxy, pyrrolyl, indolyl,carbazoyl, quinolinyl, pyridinyl, azaborolinyl, boraaryl groups, or thelike, and combinations of these. Examples of neutral ligands arecarbonyl, η⁶-aryl, η⁴-butadiene, η⁴-cyclobutadiene,η⁴-cyclooctatetraene, tertiary phosphine, and the like. Other examplesof suitable anionic or neutral ligands appear in U.S. Pat. Nos.5,756,611, 5,637,659, 5,637,660, 5,554,775, and 5,539,124, the teachingsof which are incorporated herein by reference.

[0036] In a particularly preferred embodiment of the present invention,a transition metal complex having the anionic ligand of the presentinvention is provided by structure XV:

[0037] where R¹ and R² are as provided above; R⁵ and R⁶ areindependently hydrogen, a C₁₋₁₈ alkyl group, C₆₋₁₀ aryl group, C₇₋₁₅aralkyl group, C₁₋₁₀ alkoxy group, C₆₋₁₄ aryloxy group, C₁₋₁₀dialkylamino group, or C₆₋₁₅ diarylamino group. In a refinement of thisembodiment a preferred ligand is given by formula XVI:

[0038] where R⁵ and R⁶ are as provided above; R⁷ and R⁸ areindependently a C₁₋₈ alkyl group, C₆₋₁₀ aryl group, or C₇₋₁₅ aralkylgroup. Examples of this refinement include but are not limited tocompounds given by structures XVII and XVIII:

[0039] Another particularly preferred complex is provided in structureXIX:

[0040] where Y, R¹, R², and R³ are as provided above. In a variation ofthis preferred embodiment, the anionic ligand is described by structureXX:

[0041] Still another preferred metal complex is provided by structureXXI:

[0042] where Y, M, n, R¹, R², and R³ are as provided above.

[0043] Still another preferred embodiment of the present invention, isprovided by the complex provided in structure XXII:

[0044] where Y, M, n, R¹, and R² are as provided above.

[0045] Still another preferred embodiment of the present invention, isprovided by the complex provided in structure XXIII:

[0046] where Y, M, n, R¹, and R² are as provided above.

[0047] In another embodiment of the invention, the transition metalcomplex further comprises an activator. Generally, the activatorconverts the complex to a cationically active species. The catalysts areespecially valuable for polymerizing olefins, such as ethylene,propylene, and/or other x-olefins such as 1-butene or 1-hexene. Suitableactivators are well known in the art. Preferred activators includealumoxanes (e.g., methyl alumoxane (MAO), PMAO, ethyl alumoxane,diisobutyl alumoxane), alkylaluminum compounds (triethylaluminum,diethylaluminum chloride, trimethylaluminum), and the like. Suchactivators are generally used in an amount within the range of about0.01 to about 100,000, preferably from about 1 to about 10,000, molesper mole of transition metal complex. Preferred activators also includeacid salts that contain non-nucleophilic anions. These compoundsgenerally consist of bulky ligands attached to boron or aluminum.Examples include lithium tetrakis(pentafluorophenyl) borate, lithiumtetrakis(pentafluorophenyl) aluminate, aniliniumtetrakis(pentafluorophenyl) borate, and the like. These activators aregenerally used in an amount within the range of about 0.01 to about1000, preferably from about 1 to about 10, moles per mole of transitionmetal complex. Suitable activators also include trialkyl or triarylboroncompounds such as tris(pentafluorophenyl)boron, tris(pentabromophenyl)boron, and the like. Other suitable activators are described, forexample, in U.S. Pat. Nos. 5,756,611, 5,064,802, and 5,599,761, theteachings of which are incorporated herein by reference.

[0048] The catalysts are optionally used with an inorganic solid ororganic polymer support. Suitable supports include silica, alumina,silica-aluminas, magnesia, titania, clays, zeolites, or the like. Thesupports can be pretreated thermally or chemically to improve catalystproductivity or product properties. The catalysts can be deposited onthe support in any desired manner. For instance, the catalyst can bedissolved in a solvent, combined with a support, and stripped.Alternatively, an incipient-wetness technique can be used. Moreover, thesupport can simply be introduced into the reactor separately from thecatalyst. The ligand can also be chemically tethered to the supportthrough a suitable linking group.

[0049] In yet another embodiment of the present invention, a method forforming the metal complex having the ligand of the present invention isprovided. The method comprises reacting a ligand precursor having thefollowing structure:

[0050] with a metal compound with the structure:

X—M—Ln  IV

[0051] where X is a halogen, to form metal complex II.

[0052] In another embodiment of the invention, an olefin polymerizationprocess is provided. The process comprises polymerizing an olefin in thepresence of a catalyst of the invention according to methods that arewell known in the art. Suitable techniques include gas, high-pressureliquid, slurry, solution, or suspension-phase processes and combinationsof these. Suitable olefins include ethylene, propylene, butenes,pentenes, hexenes, octenes, styrenes, 1,3-butadiene, norbornene, and thelike. Preferred olefins are ethylene, propylene, and α-olefins such as1-butene, 1-hexene, and 1-octene.

[0053] The following examples illustrate the various embodiments of thepresent invention. All reactions are carried out in an inert, air-freeatmosphere using vacuum line or dry box. All solvents are dry anddeoxygenated. Those skilled in the art will recognize many variationsthat are within the spirit of the present invention and scope of theclaims.

EXAMPLE 1 Complex Formed by Reaction of Pinacol[1-(Trimethylstannyl)ethyl] Boronate With Cyclopentadienyl ZirconiumTrichoride

[0054] A slurry of 2.63 (0.01 moles) of cyclopentadienyl zirconiumtrichloride in 100 ml of toluene at dry ice temperature is combined with3.25 g (0.01 moles) of pinacol [1-(trimethylstannyl)ethyl]boronate,prepared according to D. J. Matteson et al, Organometallics, v.4, p.1690 (1985). The mixture is gradually warmed up to room temperature andrefluxed for 24 hours. The residue after evaporation of toluene iswashed with cold hexane and used in polymerization experiments withoutfurther purification.

EXAMPLE 2 Complex Formed by Reaction of Pinacol (1-Lithioethyl)borateWith Cyclopentadienvl Zirconium

[0055] To a cold (−100° C.) solution of pinacol (1-lithioethyl)borate in100 ml of THF prepared according to reference 4 from 3.25 g (0.01 moles)of pinacol [1-(trimethylstannyl)ethyl]boronate 0.01 moles of THF complexof cyclopentadienyl zirconium trichloride is slowly added. The mixtureis gradually warmed up at room temperature and stirred for 24 hours. Theresidue after evaporation of THF is used for polymerization withoutfurther purification.

EXAMPLE 3 Preparation of A Supported Catalyst

[0056] To 2 ml of 4.1 M solution of polymethylalumoxane in toluene 0.005g of the complex formed in Example 1 is added and stirred for 1 hr atambient temperature. The resulting solution is added slowly to stirredbed of dehydrated silica support to result in a free-flowing catalystpowder.

EXAMPLE 4 Polymerization of Ethylene

[0057] About 0.25 g of the supported catalyst formed in Example 3 isadded to a 1000 ml reactor charged with 500 ml of isobutane and 1 ml of2M solution of triisobutylaluminum in heptane and ethylene ispolymerized at 350 psi ethylene pressure at 70° C. to produce highmolecular weight polyethylene.

[0058] While embodiments of the invention have been illustrated anddescribed, it is not intended that these embodiments illustrate anddescribe all possible forms of the invention. Rather, the words used inthe specification are words of description rather than limitation, andit is understood that various changes may be made without departing fromthe spirit and scope of the invention.

What is claimed is:
 1. A ligand having the formula:

where A is CH₂, CHR³, CR³R⁴, NR³, O, S, or PR³; R¹ and R² areindependently hydrogen, aryl, C₆₋₁₅ diarylphospho, C₁₋₁₈ alkylthio,C₆₋₁₅ arylthio, C₇₋₁₅ aralkyl, C₁₋₁₀ alkoxy, C₆₋₁₄ aryloxy, C₁₋₁₀dialkylamino, or C₆₋₁₅ diarylamino; and Y is B, Al, or Ga.
 2. The ligandof claim 1 having the formula:

where R⁵ and R⁶ are independently hydrogen, C₁₋₈ alkyl, C₆₋₁₀ aryl,C₇₋₁₅ aralkyl, C₁₋₁₀ alkoxy, C₆₋₁₄ aryloxy, C₁₋₁₀ dialkylamino, or C₆₋₁₅diarylamino.
 3. The ligand of claim 1 having the formula:

where R⁷ and R⁸ are independently C₁₋₈ alkyl, C₆₋₁₀ aryl, or C₇₋₁₅aralkyl.
 4. The ligand of claim 3 having the formula:


5. The ligand of claim 3 having the formula:


6. The ligand of claim 2 having the formula:

where R⁹, R¹⁰, R¹¹, and R¹² are independently C₁₋₈ alkyl, C₆₋₁₀ aryl, orC₇₋₁₅ aralkyl.
 7. The ligand of claim 1 having the formula:


8. The ligand of claim 7 having the formula:

where R⁷ and R⁸ are independently C₁₋₈ alkyl, C₆₋₁₀ aryl, or C₇₋₁₅aralkyl.
 9. The ligand of claim 1 having the formula:


10. The ligand of claim 1 having the formula:


11. The ligand of claim 1 having the formula:


12. A polymerization catalyst containing a ligand of claim 1, and havingthe formula:

where M is a transition metal; L is a sigma bonded or pi bonded ligand;n is an integer such that the valency of M is satisfied; A is CH₂, CHR³,CR³R⁴, NR³, O, S, and PR³; R¹ and R² are independently hydrogen, aryl,C₆₋₁₅ diarylphospho, C₁₋₁₈ alkylthio, C₆₋₁₅ arylthio, C₇₋₁₅ aralkyl,C₁₋₁₀ alkoxy, C₆₋₁₄ aryloxy, C₁₋₁₀ dialkylamino, or C₆₋₁₅ diarylamino;R³ and R⁴ are independently hydrogen, C₁₋₈ alkyl, C₆₋₁₀ aryl, C₇₋₁₅aralkyl, C₁₋₁₀ alkoxy, C₆₋₁₄ aryloxy, C₁₋₁₀ dialkylamino, or C₆₋₁₅diarylamino; and Y is B, Al, or Ga.
 13. The polymerization catalyst ofclaim 12 having the formula:

where: R⁵ and R⁶ are independently hydrogen, a C₁₋₈ alkyl group, C₆₋₁₀aryl group, C₇₋₁₅ aralkyl group, C₁₋₁₀ alkoxy group, C₆₋₁₄ aryloxygroup, C₁₋₁₀ dialkylamino group, or C₆₋₅ diarylamino group.
 14. Thepolymerization catalyst of claim 12 having the formula:

where R⁷ and R⁸ is hydrogen, a C₁₋₈ alkyl group, C₆₋₁₀ aryl group, orC₇₋₁₅ aralkyl group.
 15. The catalyst of claim 12 having the formula:


16. The catalyst of claim 12 having the formula:


17. The catalyst of claim 12 having the structure:


18. The catalyst of claim 12 having the formula:


19. The catalyst of claim 12 having the formula:

where R⁷ and R⁸ are independently a C₁₋₈ alkyl group, C₆₋₁₀ aryl group,or C₇₋₁₅ aralkyl group.
 20. The catalyst of claim 12 having the formula:


21. The catalyst of claim 12 having the formula:


22. The catalyst of claim 12 having the formula:


23. A process for the oligomerization or polymerization of at least oneα-olefin, said process comprising polymerizing said at least oneα-olefin in the presence of a polymerization catalyst componentcomprising the polymerization catalyst of claim
 12. 24. A polyolefin oroligoolefin prepared by the process of claim 23.